Summary.A quantitative method using precoated silica gel-60 Lichrosphere highperformance thin-layer chromatography (HPTLC) plates, automated band wise sample application, and n-hexane:acetone:formic acid (2:1:0.025 v/v/v) as mobile phase, has been developed and validated for the analysis of psoralen in marketed formulations and novel solid lipid nanoparticles (SLNs). Densitometric analysis was performed at 250 nm in absorbance mode. Compact bands of psoralen were obtained at R f 0.32 ± 0.02. The method was validated for linearity, precision, robustness, sensitivity, specificity, and recovery. Linearity (r 2 = 0.995), limit of detection (8.0 ng band −1 ), limit of quantification (18.1 ng band −1 ), recovery (98.06-99.64%), and precision (≤0.74) were satisfactory. Statistical analysis established that the developed method for quantification of psoralen in marketed formulation and from solid lipid nanoparticles is reproducible and selective.